1. Field of the Invention
The present invention relates to a magnetic recording medium and to a method of manufacturing the same. More particularly, the present invention relates to a magnetic recording medium having both good electromagnetic characteristics and frictional characteristics and to a method of manufacturing the same.
2. Discussion of the Background
In recent years, great advances have been made in means of rapidly transmitting information, permitting the transmission of data and images containing immense amounts of information. The increase in the quantity of information and enhancement of data transmission techniques have resulted in demand for higher density recording by the recording media used to record, reproduce, and store information.
Microparticulate magnetic materials and their high-degree dispersion in magnetic layers are widely employed to achieve high-density recording. The higher the degree to which a microparticulate magnetic material is dispersed, the fewer the protrusions produced by the magnetic material that are present on the surface of the magnetic layer and the greater the surface smoothness of the magnetic layer. However, the greater the surface smoothness of the magnetic layer, the greater the coefficient of friction as the reproduction head and medium slide against each other, resulting in a decrease in running durability.
Accordingly, the surface contour of the magnetic layer is controlled by adjusting the type and quantity of nonmagnetic filler (carbon black, abrasive, and the like) added to the magnetic layer (for example, see Japanese Unexamined Patent Publication (KOKAI) No. 2004-103137, which is expressly incorporated herein by reference in its entirety). Further, Japanese Unexamined Patent Publication (KOKAI) No. 2002-288816, which is expressly incorporated herein by reference in its entirety, proposes specifying the relation between the average particle diameter of the abrasive particles in the magnetic layer and the thickness of the magnetic layer to control the roughness of the magnetic layer surface.
Controlling the surface contours of the magnetic layer in the conventional manner is an effective means of reducing the actual contact area between the head and the medium to enhance frictional characteristics (lower the coefficient of friction) during signal reproduction. Additionally, when the surface contours of the magnetic layer are controlled to enhance frictional characteristics, electromagnetic characteristics may be compromised. This is because the decrease in the actual contact area between the head and the medium becomes a factor in the spacing of the head and the medium surface that leads to deterioration in electromagnetic characteristics.
Conventionally, there has thus been a tradeoff between frictional characteristics and electromagnetic characteristics, making it difficult to achieve both.